aboutsummaryrefslogtreecommitdiff
path: root/lib/dfsan/dfsan_custom.cc
blob: c58b471db53c1f91de70a99cbcaf8f8c669836d7 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
//===-- dfsan.cc ----------------------------------------------------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file is a part of DataFlowSanitizer.
//
// This file defines the custom functions listed in done_abilist.txt.
//===----------------------------------------------------------------------===//

#include "sanitizer_common/sanitizer_common.h"
#include "sanitizer_common/sanitizer_internal_defs.h"
#include "sanitizer_common/sanitizer_linux.h"

#include "dfsan/dfsan.h"

#include <arpa/inet.h>
#include <assert.h>
#include <ctype.h>
#include <dlfcn.h>
#include <link.h>
#include <poll.h>
#include <pthread.h>
#include <pwd.h>
#include <sched.h>
#include <signal.h>
#include <stdarg.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/resource.h>
#include <sys/select.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <sys/types.h>
#include <time.h>
#include <unistd.h>

using namespace __dfsan;

extern "C" {
SANITIZER_INTERFACE_ATTRIBUTE int
__dfsw_stat(const char *path, struct stat *buf, dfsan_label path_label,
            dfsan_label buf_label, dfsan_label *ret_label) {
  int ret = stat(path, buf);
  if (ret == 0)
    dfsan_set_label(0, buf, sizeof(struct stat));
  *ret_label = 0;
  return ret;
}

SANITIZER_INTERFACE_ATTRIBUTE int __dfsw_fstat(int fd, struct stat *buf,
                                               dfsan_label fd_label,
                                               dfsan_label buf_label,
                                               dfsan_label *ret_label) {
  int ret = fstat(fd, buf);
  if (ret == 0)
    dfsan_set_label(0, buf, sizeof(struct stat));
  *ret_label = 0;
  return ret;
}

SANITIZER_INTERFACE_ATTRIBUTE char *__dfsw_strchr(const char *s, int c,
                                                  dfsan_label s_label,
                                                  dfsan_label c_label,
                                                  dfsan_label *ret_label) {
  for (size_t i = 0;; ++i) {
    if (s[i] == c || s[i] == 0) {
      if (flags().strict_data_dependencies) {
        *ret_label = s_label;
      } else {
        *ret_label = dfsan_union(dfsan_read_label(s, i + 1),
                                 dfsan_union(s_label, c_label));
      }
      return s[i] == 0 ? 0 : const_cast<char *>(s+i);
    }
  }
}

SANITIZER_INTERFACE_ATTRIBUTE SANITIZER_WEAK_ATTRIBUTE
void
dfsan_weak_hook_memcmp(uptr caller_pc, const void *s1, const void *s2, size_t n,
                       dfsan_label s1_label, dfsan_label s2_label,
                       dfsan_label n_label);

SANITIZER_INTERFACE_ATTRIBUTE int __dfsw_memcmp(const void *s1, const void *s2,
                                                size_t n, dfsan_label s1_label,
                                                dfsan_label s2_label,
                                                dfsan_label n_label,
                                                dfsan_label *ret_label) {
  if (dfsan_weak_hook_memcmp)
    dfsan_weak_hook_memcmp(GET_CALLER_PC(), s1, s2, n, s1_label, s2_label,
                           n_label);
  const char *cs1 = (const char *) s1, *cs2 = (const char *) s2;
  for (size_t i = 0; i != n; ++i) {
    if (cs1[i] != cs2[i]) {
      if (flags().strict_data_dependencies) {
        *ret_label = 0;
      } else {
        *ret_label = dfsan_union(dfsan_read_label(cs1, i + 1),
                                 dfsan_read_label(cs2, i + 1));
      }
      return cs1[i] - cs2[i];
    }
  }

  if (flags().strict_data_dependencies) {
    *ret_label = 0;
  } else {
    *ret_label = dfsan_union(dfsan_read_label(cs1, n),
                             dfsan_read_label(cs2, n));
  }
  return 0;
}

SANITIZER_INTERFACE_ATTRIBUTE int __dfsw_strcmp(const char *s1, const char *s2,
                                                dfsan_label s1_label,
                                                dfsan_label s2_label,
                                                dfsan_label *ret_label) {
  for (size_t i = 0;; ++i) {
    if (s1[i] != s2[i] || s1[i] == 0 || s2[i] == 0) {
      if (flags().strict_data_dependencies) {
        *ret_label = 0;
      } else {
        *ret_label = dfsan_union(dfsan_read_label(s1, i + 1),
                                 dfsan_read_label(s2, i + 1));
      }
      return s1[i] - s2[i];
    }
  }
  return 0;
}

SANITIZER_INTERFACE_ATTRIBUTE int
__dfsw_strcasecmp(const char *s1, const char *s2, dfsan_label s1_label,
                  dfsan_label s2_label, dfsan_label *ret_label) {
  for (size_t i = 0;; ++i) {
    if (tolower(s1[i]) != tolower(s2[i]) || s1[i] == 0 || s2[i] == 0) {
      if (flags().strict_data_dependencies) {
        *ret_label = 0;
      } else {
        *ret_label = dfsan_union(dfsan_read_label(s1, i + 1),
                                 dfsan_read_label(s2, i + 1));
      }
      return s1[i] - s2[i];
    }
  }
  return 0;
}

SANITIZER_INTERFACE_ATTRIBUTE int __dfsw_strncmp(const char *s1, const char *s2,
                                                 size_t n, dfsan_label s1_label,
                                                 dfsan_label s2_label,
                                                 dfsan_label n_label,
                                                 dfsan_label *ret_label) {
  if (n == 0) {
    *ret_label = 0;
    return 0;
  }

  for (size_t i = 0;; ++i) {
    if (s1[i] != s2[i] || s1[i] == 0 || s2[i] == 0 || i == n - 1) {
      if (flags().strict_data_dependencies) {
        *ret_label = 0;
      } else {
        *ret_label = dfsan_union(dfsan_read_label(s1, i + 1),
                                 dfsan_read_label(s2, i + 1));
      }
      return s1[i] - s2[i];
    }
  }
  return 0;
}

SANITIZER_INTERFACE_ATTRIBUTE int
__dfsw_strncasecmp(const char *s1, const char *s2, size_t n,
                   dfsan_label s1_label, dfsan_label s2_label,
                   dfsan_label n_label, dfsan_label *ret_label) {
  if (n == 0) {
    *ret_label = 0;
    return 0;
  }

  for (size_t i = 0;; ++i) {
    if (tolower(s1[i]) != tolower(s2[i]) || s1[i] == 0 || s2[i] == 0 ||
        i == n - 1) {
      if (flags().strict_data_dependencies) {
        *ret_label = 0;
      } else {
        *ret_label = dfsan_union(dfsan_read_label(s1, i + 1),
                                 dfsan_read_label(s2, i + 1));
      }
      return s1[i] - s2[i];
    }
  }
  return 0;
}

SANITIZER_INTERFACE_ATTRIBUTE void *__dfsw_calloc(size_t nmemb, size_t size,
                                                  dfsan_label nmemb_label,
                                                  dfsan_label size_label,
                                                  dfsan_label *ret_label) {
  void *p = calloc(nmemb, size);
  dfsan_set_label(0, p, nmemb * size);
  *ret_label = 0;
  return p;
}

SANITIZER_INTERFACE_ATTRIBUTE size_t
__dfsw_strlen(const char *s, dfsan_label s_label, dfsan_label *ret_label) {
  size_t ret = strlen(s);
  if (flags().strict_data_dependencies) {
    *ret_label = 0;
  } else {
    *ret_label = dfsan_read_label(s, ret + 1);
  }
  return ret;
}


static void *dfsan_memcpy(void *dest, const void *src, size_t n) {
  dfsan_label *sdest = shadow_for(dest);
  const dfsan_label *ssrc = shadow_for(src);
  internal_memcpy((void *)sdest, (const void *)ssrc, n * sizeof(dfsan_label));
  return internal_memcpy(dest, src, n);
}

static void dfsan_memset(void *s, int c, dfsan_label c_label, size_t n) {
  internal_memset(s, c, n);
  dfsan_set_label(c_label, s, n);
}

SANITIZER_INTERFACE_ATTRIBUTE
void *__dfsw_memcpy(void *dest, const void *src, size_t n,
                    dfsan_label dest_label, dfsan_label src_label,
                    dfsan_label n_label, dfsan_label *ret_label) {
  *ret_label = dest_label;
  return dfsan_memcpy(dest, src, n);
}

SANITIZER_INTERFACE_ATTRIBUTE
void *__dfsw_memset(void *s, int c, size_t n,
                    dfsan_label s_label, dfsan_label c_label,
                    dfsan_label n_label, dfsan_label *ret_label) {
  dfsan_memset(s, c, c_label, n);
  *ret_label = s_label;
  return s;
}

SANITIZER_INTERFACE_ATTRIBUTE char *
__dfsw_strdup(const char *s, dfsan_label s_label, dfsan_label *ret_label) {
  size_t len = strlen(s);
  void *p = malloc(len+1);
  dfsan_memcpy(p, s, len+1);
  *ret_label = 0;
  return static_cast<char *>(p);
}

SANITIZER_INTERFACE_ATTRIBUTE char *
__dfsw_strncpy(char *s1, const char *s2, size_t n, dfsan_label s1_label,
               dfsan_label s2_label, dfsan_label n_label,
               dfsan_label *ret_label) {
  size_t len = strlen(s2);
  if (len < n) {
    dfsan_memcpy(s1, s2, len+1);
    dfsan_memset(s1+len+1, 0, 0, n-len-1);
  } else {
    dfsan_memcpy(s1, s2, n);
  }

  *ret_label = s1_label;
  return s1;
}

SANITIZER_INTERFACE_ATTRIBUTE ssize_t
__dfsw_pread(int fd, void *buf, size_t count, off_t offset,
             dfsan_label fd_label, dfsan_label buf_label,
             dfsan_label count_label, dfsan_label offset_label,
             dfsan_label *ret_label) {
  ssize_t ret = pread(fd, buf, count, offset);
  if (ret > 0)
    dfsan_set_label(0, buf, ret);
  *ret_label = 0;
  return ret;
}

SANITIZER_INTERFACE_ATTRIBUTE ssize_t
__dfsw_read(int fd, void *buf, size_t count,
             dfsan_label fd_label, dfsan_label buf_label,
             dfsan_label count_label,
             dfsan_label *ret_label) {
  ssize_t ret = read(fd, buf, count);
  if (ret > 0)
    dfsan_set_label(0, buf, ret);
  *ret_label = 0;
  return ret;
}

SANITIZER_INTERFACE_ATTRIBUTE int __dfsw_clock_gettime(clockid_t clk_id,
                                                       struct timespec *tp,
                                                       dfsan_label clk_id_label,
                                                       dfsan_label tp_label,
                                                       dfsan_label *ret_label) {
  int ret = clock_gettime(clk_id, tp);
  if (ret == 0)
    dfsan_set_label(0, tp, sizeof(struct timespec));
  *ret_label = 0;
  return ret;
}

static void unpoison(const void *ptr, uptr size) {
  dfsan_set_label(0, const_cast<void *>(ptr), size);
}

// dlopen() ultimately calls mmap() down inside the loader, which generally
// doesn't participate in dynamic symbol resolution.  Therefore we won't
// intercept its calls to mmap, and we have to hook it here.
SANITIZER_INTERFACE_ATTRIBUTE void *
__dfsw_dlopen(const char *filename, int flag, dfsan_label filename_label,
              dfsan_label flag_label, dfsan_label *ret_label) {
  void *handle = dlopen(filename, flag);
  link_map *map = GET_LINK_MAP_BY_DLOPEN_HANDLE(handle);
  if (map)
    ForEachMappedRegion(map, unpoison);
  *ret_label = 0;
  return handle;
}

struct pthread_create_info {
  void *(*start_routine_trampoline)(void *, void *, dfsan_label, dfsan_label *);
  void *start_routine;
  void *arg;
};

static void *pthread_create_cb(void *p) {
  pthread_create_info pci(*(pthread_create_info *)p);
  free(p);
  dfsan_label ret_label;
  return pci.start_routine_trampoline(pci.start_routine, pci.arg, 0,
                                      &ret_label);
}

SANITIZER_INTERFACE_ATTRIBUTE int __dfsw_pthread_create(
    pthread_t *thread, const pthread_attr_t *attr,
    void *(*start_routine_trampoline)(void *, void *, dfsan_label,
                                      dfsan_label *),
    void *start_routine, void *arg, dfsan_label thread_label,
    dfsan_label attr_label, dfsan_label start_routine_label,
    dfsan_label arg_label, dfsan_label *ret_label) {
  pthread_create_info *pci =
      (pthread_create_info *)malloc(sizeof(pthread_create_info));
  pci->start_routine_trampoline = start_routine_trampoline;
  pci->start_routine = start_routine;
  pci->arg = arg;
  int rv = pthread_create(thread, attr, pthread_create_cb, (void *)pci);
  if (rv != 0)
    free(pci);
  *ret_label = 0;
  return rv;
}

struct dl_iterate_phdr_info {
  int (*callback_trampoline)(void *callback, struct dl_phdr_info *info,
                             size_t size, void *data, dfsan_label info_label,
                             dfsan_label size_label, dfsan_label data_label,
                             dfsan_label *ret_label);
  void *callback;
  void *data;
};

int dl_iterate_phdr_cb(struct dl_phdr_info *info, size_t size, void *data) {
  dl_iterate_phdr_info *dipi = (dl_iterate_phdr_info *)data;
  dfsan_set_label(0, *info);
  dfsan_set_label(0, const_cast<char *>(info->dlpi_name),
                  strlen(info->dlpi_name) + 1);
  dfsan_set_label(
      0, const_cast<char *>(reinterpret_cast<const char *>(info->dlpi_phdr)),
      sizeof(*info->dlpi_phdr) * info->dlpi_phnum);
  dfsan_label ret_label;
  return dipi->callback_trampoline(dipi->callback, info, size, dipi->data, 0, 0,
                                   0, &ret_label);
}

SANITIZER_INTERFACE_ATTRIBUTE int __dfsw_dl_iterate_phdr(
    int (*callback_trampoline)(void *callback, struct dl_phdr_info *info,
                               size_t size, void *data, dfsan_label info_label,
                               dfsan_label size_label, dfsan_label data_label,
                               dfsan_label *ret_label),
    void *callback, void *data, dfsan_label callback_label,
    dfsan_label data_label, dfsan_label *ret_label) {
  dl_iterate_phdr_info dipi = { callback_trampoline, callback, data };
  *ret_label = 0;
  return dl_iterate_phdr(dl_iterate_phdr_cb, &dipi);
}

SANITIZER_INTERFACE_ATTRIBUTE
char *__dfsw_ctime_r(const time_t *timep, char *buf, dfsan_label timep_label,
                     dfsan_label buf_label, dfsan_label *ret_label) {
  char *ret = ctime_r(timep, buf);
  if (ret) {
    dfsan_set_label(dfsan_read_label(timep, sizeof(time_t)), buf,
                    strlen(buf) + 1);
    *ret_label = buf_label;
  } else {
    *ret_label = 0;
  }
  return ret;
}

SANITIZER_INTERFACE_ATTRIBUTE
char *__dfsw_fgets(char *s, int size, FILE *stream, dfsan_label s_label,
                   dfsan_label size_label, dfsan_label stream_label,
                   dfsan_label *ret_label) {
  char *ret = fgets(s, size, stream);
  if (ret) {
    dfsan_set_label(0, ret, strlen(ret) + 1);
    *ret_label = s_label;
  } else {
    *ret_label = 0;
  }
  return ret;
}

SANITIZER_INTERFACE_ATTRIBUTE
char *__dfsw_getcwd(char *buf, size_t size, dfsan_label buf_label,
                    dfsan_label size_label, dfsan_label *ret_label) {
  char *ret = getcwd(buf, size);
  if (ret) {
    dfsan_set_label(0, ret, strlen(ret) + 1);
    *ret_label = buf_label;
  } else {
    *ret_label = 0;
  }
  return ret;
}

SANITIZER_INTERFACE_ATTRIBUTE
char *__dfsw_get_current_dir_name(dfsan_label *ret_label) {
  char *ret = get_current_dir_name();
  if (ret) {
    dfsan_set_label(0, ret, strlen(ret) + 1);
  }
  *ret_label = 0;
  return ret;
}

SANITIZER_INTERFACE_ATTRIBUTE
int __dfsw_gethostname(char *name, size_t len, dfsan_label name_label,
                       dfsan_label len_label, dfsan_label *ret_label) {
  int ret = gethostname(name, len);
  if (ret == 0) {
    dfsan_set_label(0, name, strlen(name) + 1);
  }
  *ret_label = 0;
  return ret;
}

SANITIZER_INTERFACE_ATTRIBUTE
int __dfsw_getrlimit(int resource, struct rlimit *rlim,
                     dfsan_label resource_label, dfsan_label rlim_label,
                     dfsan_label *ret_label) {
  int ret = getrlimit(resource, rlim);
  if (ret == 0) {
    dfsan_set_label(0, rlim, sizeof(struct rlimit));
  }
  *ret_label = 0;
  return ret;
}

SANITIZER_INTERFACE_ATTRIBUTE
int __dfsw_getrusage(int who, struct rusage *usage, dfsan_label who_label,
                     dfsan_label usage_label, dfsan_label *ret_label) {
  int ret = getrusage(who, usage);
  if (ret == 0) {
    dfsan_set_label(0, usage, sizeof(struct rusage));
  }
  *ret_label = 0;
  return ret;
}

SANITIZER_INTERFACE_ATTRIBUTE
char *__dfsw_strcpy(char *dest, const char *src, dfsan_label dst_label,
                    dfsan_label src_label, dfsan_label *ret_label) {
  char *ret = strcpy(dest, src);
  if (ret) {
    internal_memcpy(shadow_for(dest), shadow_for(src),
                    sizeof(dfsan_label) * (strlen(src) + 1));
  }
  *ret_label = dst_label;
  return ret;
}

SANITIZER_INTERFACE_ATTRIBUTE
long int __dfsw_strtol(const char *nptr, char **endptr, int base,
                       dfsan_label nptr_label, dfsan_label endptr_label,
                       dfsan_label base_label, dfsan_label *ret_label) {
  char *tmp_endptr;
  long int ret = strtol(nptr, &tmp_endptr, base);
  if (endptr) {
    *endptr = tmp_endptr;
  }
  if (tmp_endptr > nptr) {
    // If *tmp_endptr is '\0' include its label as well.
    *ret_label = dfsan_union(
        base_label,
        dfsan_read_label(nptr, tmp_endptr - nptr + (*tmp_endptr ? 0 : 1)));
  } else {
    *ret_label = 0;
  }
  return ret;
}

SANITIZER_INTERFACE_ATTRIBUTE
double __dfsw_strtod(const char *nptr, char **endptr,
                       dfsan_label nptr_label, dfsan_label endptr_label,
                       dfsan_label *ret_label) {
  char *tmp_endptr;
  double ret = strtod(nptr, &tmp_endptr);
  if (endptr) {
    *endptr = tmp_endptr;
  }
  if (tmp_endptr > nptr) {
    // If *tmp_endptr is '\0' include its label as well.
    *ret_label = dfsan_read_label(
        nptr,
        tmp_endptr - nptr + (*tmp_endptr ? 0 : 1));
  } else {
    *ret_label = 0;
  }
  return ret;
}

SANITIZER_INTERFACE_ATTRIBUTE
long long int __dfsw_strtoll(const char *nptr, char **endptr, int base,
                       dfsan_label nptr_label, dfsan_label endptr_label,
                       dfsan_label base_label, dfsan_label *ret_label) {
  char *tmp_endptr;
  long long int ret = strtoll(nptr, &tmp_endptr, base);
  if (endptr) {
    *endptr = tmp_endptr;
  }
  if (tmp_endptr > nptr) {
    // If *tmp_endptr is '\0' include its label as well.
    *ret_label = dfsan_union(
        base_label,
        dfsan_read_label(nptr, tmp_endptr - nptr + (*tmp_endptr ? 0 : 1)));
  } else {
    *ret_label = 0;
  }
  return ret;
}

SANITIZER_INTERFACE_ATTRIBUTE
unsigned long int __dfsw_strtoul(const char *nptr, char **endptr, int base,
                       dfsan_label nptr_label, dfsan_label endptr_label,
                       dfsan_label base_label, dfsan_label *ret_label) {
  char *tmp_endptr;
  unsigned long int ret = strtoul(nptr, &tmp_endptr, base);
  if (endptr) {
    *endptr = tmp_endptr;
  }
  if (tmp_endptr > nptr) {
    // If *tmp_endptr is '\0' include its label as well.
    *ret_label = dfsan_union(
        base_label,
        dfsan_read_label(nptr, tmp_endptr - nptr + (*tmp_endptr ? 0 : 1)));
  } else {
    *ret_label = 0;
  }
  return ret;
}

SANITIZER_INTERFACE_ATTRIBUTE
long long unsigned int __dfsw_strtoull(const char *nptr, char **endptr,
                                       dfsan_label nptr_label,
                                       int base, dfsan_label endptr_label,
                                       dfsan_label base_label,
                                       dfsan_label *ret_label) {
  char *tmp_endptr;
  long long unsigned int ret = strtoull(nptr, &tmp_endptr, base);
  if (endptr) {
    *endptr = tmp_endptr;
  }
  if (tmp_endptr > nptr) {
    // If *tmp_endptr is '\0' include its label as well.
    *ret_label = dfsan_union(
        base_label,
        dfsan_read_label(nptr, tmp_endptr - nptr + (*tmp_endptr ? 0 : 1)));
  } else {
    *ret_label = 0;
  }
  return ret;
}

SANITIZER_INTERFACE_ATTRIBUTE
time_t __dfsw_time(time_t *t, dfsan_label t_label, dfsan_label *ret_label) {
  time_t ret = time(t);
  if (ret != (time_t) -1 && t) {
    dfsan_set_label(0, t, sizeof(time_t));
  }
  *ret_label = 0;
  return ret;
}

SANITIZER_INTERFACE_ATTRIBUTE
int __dfsw_inet_pton(int af, const char *src, void *dst, dfsan_label af_label,
                     dfsan_label src_label, dfsan_label dst_label,
                     dfsan_label *ret_label) {
  int ret = inet_pton(af, src, dst);
  if (ret == 1) {
    dfsan_set_label(dfsan_read_label(src, strlen(src) + 1), dst,
                    af == AF_INET ? sizeof(struct in_addr) : sizeof(in6_addr));
  }
  *ret_label = 0;
  return ret;
}

SANITIZER_INTERFACE_ATTRIBUTE
struct tm *__dfsw_localtime_r(const time_t *timep, struct tm *result,
                              dfsan_label timep_label, dfsan_label result_label,
                              dfsan_label *ret_label) {
  struct tm *ret = localtime_r(timep, result);
  if (ret) {
    dfsan_set_label(dfsan_read_label(timep, sizeof(time_t)), result,
                    sizeof(struct tm));
    *ret_label = result_label;
  } else {
    *ret_label = 0;
  }
  return ret;
}

SANITIZER_INTERFACE_ATTRIBUTE
int __dfsw_getpwuid_r(id_t uid, struct passwd *pwd,
                      char *buf, size_t buflen, struct passwd **result,
                      dfsan_label uid_label, dfsan_label pwd_label,
                      dfsan_label buf_label, dfsan_label buflen_label,
                      dfsan_label result_label, dfsan_label *ret_label) {
  // Store the data in pwd, the strings referenced from pwd in buf, and the
  // address of pwd in *result.  On failure, NULL is stored in *result.
  int ret = getpwuid_r(uid, pwd, buf, buflen, result);
  if (ret == 0) {
    dfsan_set_label(0, pwd, sizeof(struct passwd));
    dfsan_set_label(0, buf, strlen(buf) + 1);
  }
  *ret_label = 0;
  dfsan_set_label(0, result, sizeof(struct passwd*));
  return ret;
}

SANITIZER_INTERFACE_ATTRIBUTE
int __dfsw_poll(struct pollfd *fds, nfds_t nfds, int timeout,
                dfsan_label dfs_label, dfsan_label nfds_label,
                dfsan_label timeout_label, dfsan_label *ret_label) {
  int ret = poll(fds, nfds, timeout);
  if (ret >= 0) {
    for (; nfds > 0; --nfds) {
      dfsan_set_label(0, &fds[nfds - 1].revents, sizeof(fds[nfds - 1].revents));
    }
  }
  *ret_label = 0;
  return ret;
}

SANITIZER_INTERFACE_ATTRIBUTE
int __dfsw_select(int nfds, fd_set *readfds, fd_set *writefds,
                  fd_set *exceptfds, struct timeval *timeout,
                  dfsan_label nfds_label, dfsan_label readfds_label,
                  dfsan_label writefds_label, dfsan_label exceptfds_label,
                  dfsan_label timeout_label, dfsan_label *ret_label) {
  int ret = select(nfds, readfds, writefds, exceptfds, timeout);
  // Clear everything (also on error) since their content is either set or
  // undefined.
  if (readfds) {
    dfsan_set_label(0, readfds, sizeof(fd_set));
  }
  if (writefds) {
    dfsan_set_label(0, writefds, sizeof(fd_set));
  }
  if (exceptfds) {
    dfsan_set_label(0, exceptfds, sizeof(fd_set));
  }
  dfsan_set_label(0, timeout, sizeof(struct timeval));
  *ret_label = 0;
  return ret;
}

SANITIZER_INTERFACE_ATTRIBUTE
int __dfsw_sched_getaffinity(pid_t pid, size_t cpusetsize, cpu_set_t *mask,
                             dfsan_label pid_label,
                             dfsan_label cpusetsize_label,
                             dfsan_label mask_label, dfsan_label *ret_label) {
  int ret = sched_getaffinity(pid, cpusetsize, mask);
  if (ret == 0) {
    dfsan_set_label(0, mask, cpusetsize);
  }
  *ret_label = 0;
  return ret;
}

SANITIZER_INTERFACE_ATTRIBUTE
int __dfsw_sigemptyset(sigset_t *set, dfsan_label set_label,
                       dfsan_label *ret_label) {
  int ret = sigemptyset(set);
  dfsan_set_label(0, set, sizeof(sigset_t));
  return ret;
}

SANITIZER_INTERFACE_ATTRIBUTE
int __dfsw_sigaction(int signum, const struct sigaction *act,
                     struct sigaction *oldact, dfsan_label signum_label,
                     dfsan_label act_label, dfsan_label oldact_label,
                     dfsan_label *ret_label) {
  int ret = sigaction(signum, act, oldact);
  if (oldact) {
    dfsan_set_label(0, oldact, sizeof(struct sigaction));
  }
  *ret_label = 0;
  return ret;
}

SANITIZER_INTERFACE_ATTRIBUTE
int __dfsw_gettimeofday(struct timeval *tv, struct timezone *tz,
                        dfsan_label tv_label, dfsan_label tz_label,
                        dfsan_label *ret_label) {
  int ret = gettimeofday(tv, tz);
  if (tv) {
    dfsan_set_label(0, tv, sizeof(struct timeval));
  }
  if (tz) {
    dfsan_set_label(0, tz, sizeof(struct timezone));
  }
  *ret_label = 0;
  return ret;
}

SANITIZER_INTERFACE_ATTRIBUTE void *__dfsw_memchr(void *s, int c, size_t n,
                                                  dfsan_label s_label,
                                                  dfsan_label c_label,
                                                  dfsan_label n_label,
                                                  dfsan_label *ret_label) {
  void *ret = memchr(s, c, n);
  if (flags().strict_data_dependencies) {
    *ret_label = ret ? s_label : 0;
  } else {
    size_t len =
        ret ? reinterpret_cast<char *>(ret) - reinterpret_cast<char *>(s) + 1
            : n;
    *ret_label =
        dfsan_union(dfsan_read_label(s, len), dfsan_union(s_label, c_label));
  }
  return ret;
}

SANITIZER_INTERFACE_ATTRIBUTE char *__dfsw_strrchr(char *s, int c,
                                                   dfsan_label s_label,
                                                   dfsan_label c_label,
                                                   dfsan_label *ret_label) {
  char *ret = strrchr(s, c);
  if (flags().strict_data_dependencies) {
    *ret_label = ret ? s_label : 0;
  } else {
    *ret_label =
        dfsan_union(dfsan_read_label(s, strlen(s) + 1),
                    dfsan_union(s_label, c_label));
  }

  return ret;
}

SANITIZER_INTERFACE_ATTRIBUTE char *__dfsw_strstr(char *haystack, char *needle,
                                                  dfsan_label haystack_label,
                                                  dfsan_label needle_label,
                                                  dfsan_label *ret_label) {
  char *ret = strstr(haystack, needle);
  if (flags().strict_data_dependencies) {
    *ret_label = ret ? haystack_label : 0;
  } else {
    size_t len = ret ? ret + strlen(needle) - haystack : strlen(haystack) + 1;
    *ret_label =
        dfsan_union(dfsan_read_label(haystack, len),
                    dfsan_union(dfsan_read_label(needle, strlen(needle) + 1),
                                dfsan_union(haystack_label, needle_label)));
  }

  return ret;
}

SANITIZER_INTERFACE_ATTRIBUTE int __dfsw_nanosleep(const struct timespec *req,
                                                   struct timespec *rem,
                                                   dfsan_label req_label,
                                                   dfsan_label rem_label,
                                                   dfsan_label *ret_label) {
  int ret = nanosleep(req, rem);
  *ret_label = 0;
  if (ret == -1) {
    // Interrupted by a signal, rem is filled with the remaining time.
    dfsan_set_label(0, rem, sizeof(struct timespec));
  }
  return ret;
}

SANITIZER_INTERFACE_ATTRIBUTE int
__dfsw_socketpair(int domain, int type, int protocol, int sv[2],
                  dfsan_label domain_label, dfsan_label type_label,
                  dfsan_label protocol_label, dfsan_label sv_label,
                  dfsan_label *ret_label) {
  int ret = socketpair(domain, type, protocol, sv);
  *ret_label = 0;
  if (ret == 0) {
    dfsan_set_label(0, sv, sizeof(*sv) * 2);
  }
  return ret;
}

// Type of the trampoline function passed to the custom version of
// dfsan_set_write_callback.
typedef void (*write_trampoline_t)(
    void *callback,
    int fd, const void *buf, ssize_t count,
    dfsan_label fd_label, dfsan_label buf_label, dfsan_label count_label);

// Calls to dfsan_set_write_callback() set the values in this struct.
// Calls to the custom version of write() read (and invoke) them.
static struct {
  write_trampoline_t write_callback_trampoline = NULL;
  void *write_callback = NULL;
} write_callback_info;

SANITIZER_INTERFACE_ATTRIBUTE void
__dfsw_dfsan_set_write_callback(
    write_trampoline_t write_callback_trampoline,
    void *write_callback,
    dfsan_label write_callback_label,
    dfsan_label *ret_label) {
  write_callback_info.write_callback_trampoline = write_callback_trampoline;
  write_callback_info.write_callback = write_callback;
}

SANITIZER_INTERFACE_ATTRIBUTE int
__dfsw_write(int fd, const void *buf, size_t count,
             dfsan_label fd_label, dfsan_label buf_label,
             dfsan_label count_label, dfsan_label *ret_label) {
  if (write_callback_info.write_callback != NULL) {
    write_callback_info.write_callback_trampoline(
        write_callback_info.write_callback,
        fd, buf, count,
        fd_label, buf_label, count_label);
  }

  *ret_label = 0;
  return write(fd, buf, count);
}
}

// Type used to extract a dfsan_label with va_arg()
typedef int dfsan_label_va;

// Formats a chunk either a constant string or a single format directive (e.g.,
// '%.3f').
struct Formatter {
  Formatter(char *str_, const char *fmt_, size_t size_)
      : str(str_), str_off(0), size(size_), fmt_start(fmt_), fmt_cur(fmt_),
        width(-1) {}

  int format() {
    char *tmp_fmt = build_format_string();
    int retval =
        snprintf(str + str_off, str_off < size ? size - str_off : 0, tmp_fmt,
                 0 /* used only to avoid warnings */);
    free(tmp_fmt);
    return retval;
  }

  template <typename T> int format(T arg) {
    char *tmp_fmt = build_format_string();
    int retval;
    if (width >= 0) {
      retval = snprintf(str + str_off, str_off < size ? size - str_off : 0,
                        tmp_fmt, width, arg);
    } else {
      retval = snprintf(str + str_off, str_off < size ? size - str_off : 0,
                        tmp_fmt, arg);
    }
    free(tmp_fmt);
    return retval;
  }

  char *build_format_string() {
    size_t fmt_size = fmt_cur - fmt_start + 1;
    char *new_fmt = (char *)malloc(fmt_size + 1);
    assert(new_fmt);
    internal_memcpy(new_fmt, fmt_start, fmt_size);
    new_fmt[fmt_size] = '\0';
    return new_fmt;
  }

  char *str_cur() { return str + str_off; }

  size_t num_written_bytes(int retval) {
    if (retval < 0) {
      return 0;
    }

    size_t num_avail = str_off < size ? size - str_off : 0;
    if (num_avail == 0) {
      return 0;
    }

    size_t num_written = retval;
    // A return value of {v,}snprintf of size or more means that the output was
    // truncated.
    if (num_written >= num_avail) {
      num_written -= num_avail;
    }

    return num_written;
  }

  char *str;
  size_t str_off;
  size_t size;
  const char *fmt_start;
  const char *fmt_cur;
  int width;
};

// Formats the input and propagates the input labels to the output. The output
// is stored in 'str'. 'size' bounds the number of output bytes. 'format' and
// 'ap' are the format string and the list of arguments for formatting. Returns
// the return value vsnprintf would return.
//
// The function tokenizes the format string in chunks representing either a
// constant string or a single format directive (e.g., '%.3f') and formats each
// chunk independently into the output string. This approach allows to figure
// out which bytes of the output string depends on which argument and thus to
// propagate labels more precisely.
//
// WARNING: This implementation does not support conversion specifiers with
// positional arguments.
static int format_buffer(char *str, size_t size, const char *fmt,
                         dfsan_label *va_labels, dfsan_label *ret_label,
                         va_list ap) {
  Formatter formatter(str, fmt, size);

  while (*formatter.fmt_cur) {
    formatter.fmt_start = formatter.fmt_cur;
    formatter.width = -1;
    int retval = 0;

    if (*formatter.fmt_cur != '%') {
      // Ordinary character. Consume all the characters until a '%' or the end
      // of the string.
      for (; *(formatter.fmt_cur + 1) && *(formatter.fmt_cur + 1) != '%';
           ++formatter.fmt_cur) {}
      retval = formatter.format();
      dfsan_set_label(0, formatter.str_cur(),
                      formatter.num_written_bytes(retval));
    } else {
      // Conversion directive. Consume all the characters until a conversion
      // specifier or the end of the string.
      bool end_fmt = false;
      for (; *formatter.fmt_cur && !end_fmt; ) {
        switch (*++formatter.fmt_cur) {
        case 'd':
        case 'i':
        case 'o':
        case 'u':
        case 'x':
        case 'X':
          switch (*(formatter.fmt_cur - 1)) {
          case 'h':
            // Also covers the 'hh' case (since the size of the arg is still
            // an int).
            retval = formatter.format(va_arg(ap, int));
            break;
          case 'l':
            if (formatter.fmt_cur - formatter.fmt_start >= 2 &&
                *(formatter.fmt_cur - 2) == 'l') {
              retval = formatter.format(va_arg(ap, long long int));
            } else {
              retval = formatter.format(va_arg(ap, long int));
            }
            break;
          case 'q':
            retval = formatter.format(va_arg(ap, long long int));
            break;
          case 'j':
            retval = formatter.format(va_arg(ap, intmax_t));
            break;
          case 'z':
          case 't':
            retval = formatter.format(va_arg(ap, size_t));
            break;
          default:
            retval = formatter.format(va_arg(ap, int));
          }
          dfsan_set_label(*va_labels++, formatter.str_cur(),
                          formatter.num_written_bytes(retval));
          end_fmt = true;
          break;

        case 'a':
        case 'A':
        case 'e':
        case 'E':
        case 'f':
        case 'F':
        case 'g':
        case 'G':
          if (*(formatter.fmt_cur - 1) == 'L') {
            retval = formatter.format(va_arg(ap, long double));
          } else {
            retval = formatter.format(va_arg(ap, double));
          }
          dfsan_set_label(*va_labels++, formatter.str_cur(),
                          formatter.num_written_bytes(retval));
          end_fmt = true;
          break;

        case 'c':
          retval = formatter.format(va_arg(ap, int));
          dfsan_set_label(*va_labels++, formatter.str_cur(),
                          formatter.num_written_bytes(retval));
          end_fmt = true;
          break;

        case 's': {
          char *arg = va_arg(ap, char *);
          retval = formatter.format(arg);
          va_labels++;
          internal_memcpy(shadow_for(formatter.str_cur()), shadow_for(arg),
                          sizeof(dfsan_label) *
                              formatter.num_written_bytes(retval));
          end_fmt = true;
          break;
        }

        case 'p':
          retval = formatter.format(va_arg(ap, void *));
          dfsan_set_label(*va_labels++, formatter.str_cur(),
                          formatter.num_written_bytes(retval));
          end_fmt = true;
          break;

        case 'n': {
          int *ptr = va_arg(ap, int *);
          *ptr = (int)formatter.str_off;
          va_labels++;
          dfsan_set_label(0, ptr, sizeof(ptr));
          end_fmt = true;
          break;
        }

        case '%':
          retval = formatter.format();
          dfsan_set_label(0, formatter.str_cur(),
                          formatter.num_written_bytes(retval));
          end_fmt = true;
          break;

        case '*':
          formatter.width = va_arg(ap, int);
          va_labels++;
          break;

        default:
          break;
        }
      }
    }

    if (retval < 0) {
      return retval;
    }

    formatter.fmt_cur++;
    formatter.str_off += retval;
  }

  *ret_label = 0;

  // Number of bytes written in total.
  return formatter.str_off;
}

extern "C" {
SANITIZER_INTERFACE_ATTRIBUTE
int __dfsw_sprintf(char *str, const char *format, dfsan_label str_label,
                   dfsan_label format_label, dfsan_label *va_labels,
                   dfsan_label *ret_label, ...) {
  va_list ap;
  va_start(ap, ret_label);
  int ret = format_buffer(str, ~0ul, format, va_labels, ret_label, ap);
  va_end(ap);
  return ret;
}

SANITIZER_INTERFACE_ATTRIBUTE
int __dfsw_snprintf(char *str, size_t size, const char *format,
                    dfsan_label str_label, dfsan_label size_label,
                    dfsan_label format_label, dfsan_label *va_labels,
                    dfsan_label *ret_label, ...) {
  va_list ap;
  va_start(ap, ret_label);
  int ret = format_buffer(str, size, format, va_labels, ret_label, ap);
  va_end(ap);
  return ret;
}
}